This would be a great adult book club book, not only for the discussion of the story, but to discuss Updike's mastery of description and insight into human behavior. I would follow the discussion with a movie night viewing of The Witches of Eastwick with flowing adult beverages.
This would not be a good book for high school discussions, and would likely insult the heck out of anyone who isn't open to discuss the self centered wicked lives of the coven. Morals are not held up in any high standards, though there is a fair amount of regret tied to bad witchie choices.
Lastly, Mr. Updike has a sequel published in 2008, The Widows of Eastwick. I have not read this yet, but wonder why he waited so long to write part two! The Amazon reviews are not as high as they are for the The Witches of Eastwick
Updike has many other great novels under his belt, so if this selection doesn't appeal to your sensibilities, there are many other great novels such as his famous Rabbit series. I found a complete list on wikipedia:
http://en.wikipedia.org/wiki/Category:Novels_by_John_Updike.
Happy Bookclub Reading! Katherine.